A body of research exists investigating the effects of cocaine on schedule-controlled behavior in pigeons using food reinforcement. Although a variety of studies have explored the effects of psychomotor stimulants on eating, no data currently exists on the effects of cocaine on eating by pigeons when food is presented for limited durations as done in typical operant experiments. All previous studies have used rats as subjects and had food available continuously throughout the entire session. The current proposal will assess the acute and chronic effects of cocaine in addition to the effects of cocaine after a prolonged period of time without cocaine on eating by pigeons. Six pigeons in Experiment 1 will be exposed to a variable-time schedule of food delivery. Two groups of pigeons in Experiment 2 will be exposed to a three-component multiple fixed-time schedule of food delivery with different inter-food presentation times. The Before Group will receive chronic administrations of cocaine prior to session while the After Group will receive cocaine immediately following session. The results of both experiments will clarify any mediating effects of eating on tolerance to cocaine's effects in schedule-controlled behavior. Additionally, the behavioral mechanisms of tolerance to cocaine in eating will be investigated.